KR20090082311A - Fuel supply system of internal combustion engine - Google Patents

Abstract

A fuel supply system of an internal combustion engine is provided to keep the airtightness even when a loss or leakage occurs in the high pressure fuel line and to thereby ensure an emergency operation of the engine. A fuel supply system of an internal combustion engine comprises a first sealing element(18) which is located between a casing(15) and a connector(11) of each high pressure fuel line(10), and a second sealing element(22) which is located between the casing and a clamp screw(19) of each high pressure fuel line. The clamp screw is coupled to the connector, surrounding the casing. The first sealing element is made of U-shaped sealing material in which a V-shaped prestressing element is inserted. The second sealing element is a clamp ring.

Description

FUEL SUPPLY SYSTEM OF INTERNAL COMBUSTION ENGINE}

The present invention relates to a fuel supply system of an internal combustion engine, ie a common rail fuel supply system, according to the preamble of claim 1.

German Patent No. 101 57 135 B4 discloses an internal combustion engine with a plurality of cylinders, ie a marine diesel internal combustion engine operated with heavy oil, each cylinder being assigned a common-rail fuel supply system. Each cylinder of the internal combustion engine may be fuel injected by an injector. The common-rail fuel supply system according to German Patent No. 101 57 135 B4 is equipped with a plurality of high pressure pumps for feeding fuel from the low pressure section of the common-rail fuel supply system to the high pressure section of the common-rail fuel supply system. A pump device is provided, in which a high pressure zone between the pump device and the injector is provided with a accumulator system which is constantly at high pressure. According to German Patent No. 101 57 135 B4, the normally high pressure accumulator system, also referred to as the common-rail, has a plurality of storage units and also via a high pressure fuel line which is also constantly at high pressure. It is connected to the pump device. In addition, the accumulator system is connected to the injector via a high pressure fuel line which is temporarily in a high pressure state depending on the injection stroke.

The parts of the high pressure zone of such a common-rail fuel supply system are subjected to high operating pressures which can reach 2000 bar during operation. As a result, in particular, stringent requirements are placed on the sealing of parts of the common-rail fuel supply system which are constantly in high pressure.

It is even more so in the case of marine diesel internal combustion engines, since the family of parts of the common-rail fuel supply system of marine diesel internal combustion engines is subjected to additional loads, ie high vibrational stresses and high thermal stresses, in addition to high operating pressures. It can cause line rupture and thus large leakage, especially in the region of the constantly high pressure fuel line which connects the pump device to the accumulator system of the common-rail fuel supply system.

If large leaks occur in the components of the common-rail fuel supply system that are constantly in high pressure, the pressure in the high-pressure region of the fuel supply system falls to the cylinder of the internal combustion engine due to the drop in pressure below the opening pressure necessary to open the injector. This can result in the injection of no longer being possible. It results in an immediate shutdown of the internal combustion engine, which can lead to situations that are not maneuverable, for example in ships equipped only with internal combustion engines having such a fuel supply system.

In order to account for the problem of large leaks in the high-pressure zone of the common-rail fuel supply system, high pressure pumps are connected to the accumulator system via two high pressure fuel lines, and the fuel supply is shut off at the time of line rupture. It is already known from EP 1 143 140 B1 to attach a shut-off valve to the end of the high pressure fuel lines which prevents a pressure drop in the high pressure zone of the system. However, the construction of the fuel supply system is structurally complicated by providing redundant spare lines between the high pressure pump and the accumulator system of the common-rail fuel supply system. This also increases the structural space that the fuel supply system requires in the internal combustion engine.

It is an object of the present invention, starting from such prior art, to provide a new fuel supply system of an internal combustion engine, namely a new common-rail fuel supply system.

Such an object is achieved by a fuel supply system according to claim 1. According to the invention, the normally high pressure fuel lines or opposing ends of each such high pressure fuel line connecting the pump device to the accumulator system are connected to and / or connected to the pump device or accumulator system by respective connectors. The opposing ends of the temporarily high pressure fuel line or each such high pressure fuel line connecting the accumulator system to the injector are connected to the accumulator system or each injector by respective connectors, the casing of each high pressure fuel line Each high pressure fuel line such that a first sealing element is located between the connector and the connector, and a second sealing element is located between the casing of each high pressure fuel line and a clamp screw surrounding the casing from the radially outer side and screwed to the connector. Opposite ends of are connected.

By casing each high-pressure fuel line and consistently sealing the high-pressure fuel line that surrounds the casing to the connector, a secure seal can be ensured even if loss or leakage occurs in the high-pressure fuel line of the fuel supply system, This ensures that emergency operation of the internal combustion engine fueled at least through the fuel supply system can be maintained. To that end, the casing enclosed high pressure fuel line is doubled, and thus redundantly sealed, against the connector or clamp screw screwed to the connector.

The first sealing element is located between the casing of the high pressure fuel line and the connector, and the second sealing element is located between the casing of the high pressure fuel line and the clamp screw. This ensures an emergency operating pressure on the fuel supply system even if the first sealing element is not functioning, thereby ensuring subsequent or emergency operation of the internal combustion engine fueled through the fuel supply system. It becomes possible.

According to a preferred improved construction of the invention, a support ring is provided in which the first section protrudes into the free space formed between the casing and the clamp screw and the second section protrudes into the free space formed between the casing and the connector. Located between the sealing element and the second sealing element.

The fuel supply system of the internal combustion engine according to the present invention is configured to enclose a casing on each high pressure fuel line and to reliably seal the high pressure fuel line in which the casing is enclosed to the connector, thereby causing a loss or leakage in the high pressure fuel line of the fuel supply system. In this case, a secure seal can be ensured, thereby ensuring that emergency operation of the internal combustion engine fueled at least through the fuel supply system can be maintained. The high pressure fuel line in which the casing is enclosed is doubled, and thus redundantly sealed, to the clamp screw screwed to the connector or the connector by the first and second sealing elements. The first sealing element is located between the casing of the high pressure fuel line and the connector, and the second sealing element is located between the casing of the high pressure fuel line and the clamp screw. This ensures an emergency operating pressure on the fuel supply system even if the first sealing element is not functioning, thereby ensuring subsequent or emergency operation of the internal combustion engine fueled through the fuel supply system. It becomes possible.

It will be apparent from the dependent claims and the following description that the preferred improved constructions of the invention. Hereinafter, embodiments of the present invention will be described in more detail based on the accompanying drawings without being limited thereto.

The present invention relates to a common-rail fuel supply system of an internal combustion engine, in particular a marine diesel internal combustion engine operated with heavy oil. The common-rail fuel supply system has a low pressure zone and a high pressure zone.

The high pressure zone of the common-rail fuel supply system includes a pump device with one or more high pressure pumps and a accumulator system with one or more storage units, the pump device being connected to the accumulator system via one or more high pressure fuel lines. The accumulator system and the high pressure fuel line connecting the accumulator system or each such accumulator system to the pump device are in a high operating pressure state which can constantly reach 2000 bar. Fuel may be injected from the accumulator system and injected by the injectors into the cylinder of the internal combustion engine, each injector being supplied to the accumulator system via one or more high pressure fuel lines which are temporarily in high pressure depending on the injection stroke of the internal combustion engine. Connected.

In the high pressure zone of the common-rail fuel supply system, the high-pressure of the common-rail fuel supply unit is designed to open the injector to avoid lowering the operating pressure below the opening pressure required to inject fuel into the cylinder of the internal combustion engine. Temporarily high pressure fuel lines which are constantly in high pressure or which connect each respective high pressure fuel line and / or accumulator system to the injector, connecting the pump device of the zone to the accumulator system of the high-pressure zone of the common-rail fuel supply. A casing is attached to the high pressure fuel line or each such high pressure fuel line that is in a condition, the casing having a wall thickness that allows it to withstand emergency operating pressures. The emergency operating pressure is higher than the open pressure of the injector. Thereby, lowering of the operating pressure below the opening pressure of the injector at the time of line rupture of the high-pressure fuel line can be avoided, and emergency operation of the internal combustion engine by the common-rail fuel supply can be ensured. The emergency operating pressure is above 400 bar, in particular above 800 bar.

1 is a cross-sectional view of a common-rail fuel supply device according to a first embodiment of the present invention in the region of the end of the high-pressure fuel line 10 which is constantly in a high-pressure state. The end of 10 is connected to the accumulator system 13 of the common-rail fuel supply system by a connector 11 and a spring catch 12. The high pressure fuel line 10 has a pressure tube 14 and a casing 15, the casing 15 having a casing in the event that the pressure tube 14 ruptures and there is a large amount of leakage of the pressure tube 14. 15) has a wall thickness to withstand the specified emergency operating pressure.

The casing 15 is configured such that a gap of 0.1 mm to 0.2 mm remains between the inner wall of the casing 15 and the outer wall of the pressure tube 14 of the high pressure fuel line. Thus, the inner diameter of the casing 15 is chosen slightly larger than the outer diameter of the pressure tube 14 of the high pressure fuel line.

The flow channel formed by the inner wall of the casing 15 and the outer wall of the pressure tube 14 allows a small amount of fuel leakage to be transferred to the fuel tank during normal operation of the fuel supply apparatus in which the pressure tube 14 is not ruptured. Thus it serves to return to the low pressure zone of the fuel supply device, for which a leak return line 16 is integrated into the accumulator system 13, according to FIG. 1. In order to be able to maintain the emergency operating pressure in the event of a large leak, the pressure tube 14 bursts, the leak return line 16 incorporates a shutoff device 17 formed as a throttle, the shutoff device Will cause backflow in the event of a large leak to provide emergency operating pressure. As a result, the shutoff device 17 isolates the high pressure fuel line 10 from the low pressure zone of the fuel supply device.

The sealing area between the high pressure fuel line 10 and the connector 11 in which the casing is enclosed is overlapped by two sealing devices, between the casing 15 and the connector 11 of the high pressure fuel line 10. A first sealing element 18 is located between the clamp screw 19 which is screwed into the female threaded portion 21 of the connector 11 by the casing 15 of the high pressure fuel line 10 and the male threaded portion 20. In the second seal element 22 is located. The clamp screw 19, the second sealing element 22, and the first sealing element 18 surround the casing 15 of the high pressure fuel line 10, respectively, radially outward.

The first sealing element 18 preferably consists of an asymmetrical seal, preferably a U-shaped seal, into which the U-shaped prestressing element is preferably inserted. Preferably, the seal of the first sealing element 18 is formed of PTFE material, and the prestressing element of the first sealing element 18 is preferably formed of a metal spring. The second sealing element 22 is formed as a clamp ring and is preferably formed of a PTFE-bronze composite material.

According to FIG. 1, a support ring 23 is located between the first sealing element 18 and the second sealing element 22, which also supports the high pressure fuel line 10 at the radially outward side. Partially surround the casing 15. The first section of the support ring 23 protrudes into a free space formed between the casing 15 and the clamp screw 19, and the opposite section of the support ring 23 is located between the casing 15 and the connector 11. Protrude into the free space to be formed. As can be seen from FIG. 1, the mobility of the support ring 23 towards the first sealing element 18 is limited by the stopper 24 formed by the connector 11, the support ring 23 having its protrusions. As a result, the stopper 24 comes into contact with the stopper 24. Towards the second sealing element 22, the mobility of the support ring 23 is limited by the conical outline 25 of the clamp screw 19.

In normal operation where the high pressure fuel line 10 is not ruptured, the first sealing element 18 can be freely moved in the axial direction so that the support ring 23 does not press against the first sealing element 18. In that case, the clamp screw 19 presses only the second sealing element 22. That is, only the second sealing element 22 is pressed so that there is a constant gap between the support ring 23 and the second sealing element 22 formed as the clamp ring. In the event of a leak in the high pressure fuel line 10, the first sealing element 18 presses the support ring 23. The support ring 23 then presses on the second sealing element 22, in which case the mobility of the support ring 23 towards the second sealing element 22 is at the periphery 25 of the clamp screw 19. Will be limited by). In that case, due to the constant pressing of the second sealing element 18 by the support ring 23, the prestress of the second sealing element 22 rises, so that its sealing action is improved and the first sealing element ( If only 18) cannot withstand the emergency operating pressure, an additional sealing function is provided by the second sealing element 22.

Thus, the sealing portion between the high pressure fuel line 10 and the connector 11 is provided with a redundant sealing system comprising the first sealing element 18 and the second sealing element 22. It is preferable that the sealing element 18 is a spring prestressed sealing body whose material has excellent fuel resistance, temperature resistance, and aging resistance. Behind the first sealing element 18 is arranged a second sealing element 22 made of plastic having fuel resistance and temperature resistance.

The second sealing element 22 has an overdiameter portion with respect to the clamp screw 19, so that the assembly is made to fill the gap between the clamp screw 19 and the casing 15 of the high pressure fuel line 10 during assembly. 2 sealing element 22 is to be compressed.

If the high pressure fuel line 10 is not sealed because the first sealing element 18 is not functioning properly, the fuel pressure is applied to the end face of the second sealing element 22, in which case the pressure increases. The periphery of the clamp screw 19 and the corresponding periphery of the second sealing element 22 cause a self-sealing action so that the sealing action of the second sealing element 22 is increased, which is reduced by the second sealing element. Because it is pressed into the gap.

The support ring 23 located between the first sealing element 18 and the second sealing element 22 is made of a metallic material, and the second sealing element 22 is within a certain limit of the first sealing element 18. When the pressure is increased as a result of a leak in the high pressure fuel line 10 and the second sealing element 22 is supported by the connector 11 via the support ring 23, the first sealing element ( 22) is preferably configured to be compressed.

The connector 11 is screwed with the female threaded portion 27 of the accumulator system 13 by the male threaded portion 26, with a third seal between the connector 11 and the accumulator system 13 in the region adjacent the screwed portion. Element 28 is located. In the embodiment of FIG. 1, it is preferred that the third sealing element 28 is an asymmetrical seal, preferably a U-shaped seal, wherein the U-shaped seal preferably has a V-shaped metal prestressing element. Is inserted. According to FIG. 1, the support ring 29 cooperates with such a sealing element 28. The threaded section formed by the male threaded portion 26 of the connector 11 and the female threaded portion 27 of the accumulator system 13 acts as another sealing element or throttle element. In the case of a leak of the high pressure fuel line 10, the amount of leakage flowing through such a screw section is so small that the emergency operation of the internal combustion engine can be maintained even at a fuel pressure of 2000 bar. In essence, the use of such screw sealing means can realize even a complete seal in the screw area.

FIG. 2 shows a second embodiment of the present invention, in which the embodiment of FIG. 2 substantially coincides with the embodiment of FIG. Therefore, in order to avoid unnecessary repetition, the same reference numerals are used for the same component group, and hereinafter, only the details for distinguishing the embodiment of FIG. 2 from the embodiment of FIG. 1 will be described.

That is, in the embodiment of FIG. 2, the third sealing element 28 ′ is configured as a conventional circular sealing ring and a pressureless discharging line 30 is provided, where the pressureless discharging line 30 is a accumulator system 13. ) And communicates with the hollow space formed between the connector 11 and the accumulator system 13 to protect the third sealing element 28 'from unacceptable high pressure stresses.

1 is a cross-sectional view showing a fuel supply system of an internal combustion engine of the present invention according to a first embodiment of the present invention;

2 is a cross-sectional view showing a fuel supply system of an internal combustion engine of the present invention according to a second embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: high pressure fuel line 11: connector

12: spring catch 13: accumulator system

14: pressure tube 15: casing

16: Leakage return line 17: Shutoff device

18: first sealing element 19: clamp screw

20, 26: male thread portion 21, 27: female thread portion

22: second sealing element 23, 29: support ring

24: stopper 25: outer part

28, 28 ': third sealing element 30: take-out line

Claims (13)

A fuel supply system, ie a common-rail fuel supply system of an internal combustion engine, in particular a marine diesel internal combustion engine, comprising one or more high pressure pumps for feeding fuel from the low pressure zone and the low pressure zone of the fuel supply system to the high pressure zone of the fuel supply system. An accumulator system having a pumping device, comprising a pumping device, having at least one storage unit and being constantly at high pressure, is provided in the high pressure zone between the pump device and the injector assigned to the cylinder, and the accumulating system is also constantly at high pressure. In a fuel supply system of an internal combustion engine connected to a pump device via a high pressure fuel line, the accumulator system is connected to the injector via a high pressure fuel line in a temporarily high pressure state depending on the injection stroke, Normally high pressure fuel lines 10 or opposing ends of each such high pressure fuel line 10 connecting the pump device to the accumulator system are connected to the pump device or accumulator system by respective connectors 11. And / or opposing ends of the temporarily high pressure fuel line 10 or each such high pressure fuel line 10 that connects the accumulator system to the injector are connected to the accumulator system or each by means of a respective connector 11. A first sealing element 18 is located between the connector 11 and the casing 15 of each high pressure fuel line 10, the casing 15 of each high pressure fuel line 10. And opposite ends of each of the high pressure fuel lines 10 such that the second sealing element 22 is positioned between the clamp screw 19, which is enclosed in its casing 15 and screwed to the connector 11, radially outwardly. Connected The fuel supply system, characterized in that. 2. The sealing element according to claim 1, wherein the first sealing element 18 consists of a seal, preferably a U-shaped seal, which preferably is asymmetrical, and the U-shaped seal preferably comprises a V-shaped prestressing element. A fuel supply system, characterized in that it is inserted. 3. A fuel supply system according to claim 2, wherein the seal of the first sealing element (18) is formed of PTFE material and the prestressing element of the first sealing element (18) is formed of a metal spring. 4. The fuel supply system according to claim 1, wherein the second sealing element is formed as a clamp ring. 5. 5. A fuel supply system according to claim 4, wherein the clamp ring of the second sealing element (22) is formed of a PTFE-bronze composite material. 6. The support ring 23 according to claim 1, wherein the support ring 23 is located between the first sealing element 18 and the second sealing element 22. Protrudes into a free space formed between the casing 15 and the clamp screw 19, and the second section of the support ring 23 protrudes into a free space formed between the casing 15 and the connector 11. Fuel supply system made with gong. 7. A fuel supply system according to claim 6, wherein the first sealing element (18) is freely movable in the axial direction so that the support ring (23) does not press the first sealing element (18). Fuel supply according to claim 6 or 7, wherein the clamp screw (19) presses the second sealing element (22) such that there is a gap between the support ring (23) and the second sealing element (22). system. 9. The pump device or accumulator according to claim 1, wherein the connector 11 is positioned such that the third sealing element 28, 28 is located between the connector 11 and the pump device or accumulator system or injector. A fuel supply system, characterized in that connected to the system or injector. 10. The sealing element according to claim 9, wherein the third sealing element 28 consists of a seal, preferably a U-shaped seal, which is preferably asymmetrical, in which the U-shaped seal is preferably inserted with a V-shaped prestressing element. A fuel supply system characterized by the above. 10. The third sealing element 28 'is made as a sealing ring and communicates with a hollow space formed between the connector 11 and the pump device or the accumulator system or the injector. And a pressureless discharge line (30) to protect the sealing ring from unacceptable high pressure stresses. The high pressure fuel line 10 or each of those high pressure fuel lines 10 and / or the pressure accumulating system according to any one of claims 1 to 11, which is in a constantly high pressure state connecting the pump device to the accumulating system. The high pressure fuel line 10 or the respective high pressure fuel lines 10 which are in a temporary high pressure state which connects them to the injector and are enclosed in their respective high pressure fuel lines to withstand a constant emergency operating pressure. Fuel supply system characterized by having a wall thickness 13. A fuel supply system according to claim 12, wherein the constant emergency operating pressure is greater than the opening pressure of the injector, but at least 400 bar, in particular at least 800 bar.

Images